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<script>
    function flattenArr(arr){
        let result = [];
        for(let i=0;i<arr.length;i++){
            if(arr[i] instanceof Array){
                result = result.concat(flattenArr(i));
            }else{
                result.push(arr[i]);
            }
        }
        return  result;
    }
    // 将多维数组
    var arr = [
        [1, 2, 2],
        [3, 4, 5, 5],
        [6, 7, 8, 9, [11, 12, [12, 13, [14]]]], 10
    ];
    // 转为一维数组 [1, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12, 13, 14, 10]
    // 提示：需要使用 instanceof判断是否为数组 并且使用递归
     console.log(arr instanceof Array);
     console.log(typeof arr);
     var flatarr = flattenArr(arr);
     console.log(flatarr);
     flattenArr(arr);
</script>

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